• Restorative Dentistry and Endodontics
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• v.16 no.1
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• pp.87-105
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• 1991

The purpose of this experiment was to measure the leaking and solubility of commonly used dental restorative materials - Silux plus (CS), Hi-pol (CH), Clearfil F-II, Fissureseal (FS), Glass-Ionomer cement Fuji Type II (GI), Amalgam Cavex 68 (AM), Zinc Phosphate Cement (ZP) and gutta-percha (GP) and investigate the relation between the solubility and marginal leakage. Disc-shape specimens were fabricated with each material and dipped into deionized water, 0.01M lactic acid and 0.005M KOH solution, thus the total ionic concentrations in each solution was measured with ion chromatograph after 1, 3, and 7 days, respectively. For the solubility test, each specimen was immersed in 0.001M and 0.01M lactic acid for 24 hours, respectively and total weight loss was calculated. Also, Zn leaking through the margin of restorations was measured. The obtained results were as follows: 1. The amounts of eluted ion from the eight materials were most in 0.01M lactic acid and least in deionized water. 2. Of the eight materials, the fluoride release was greatest for glass ionomer cement (GI) in 0.01 M lactic acid after 7 days. 3. In analysis of the divalent cation, Mg was eluted most for zinc phosphate cement (ZP) and Ca for Clearfil F-II (CF) in 0.01M lactic acid after 7 days. 4. In analysis of transition metals, Cu and Zn were detected only. 5. The solubility rate of eight materials was greater in 0.01M lactic acid than in 0.001M for 24 hours, for zinc phosphate cement (ZP) the rate was greatest (5.4%) in 0.001M lactic acid, and amalgam least (0.01%). 6. The Zn concentration of restorative material with Z.P.C base was greater in 0.01M lactic acid than in 0.001M lactic acid.

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.721-727
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• 1998

An analytical method for simultaneous and rapid determination of organophosphorus, organochlorine, carbamate, and pyrethroid pesticides in polished rice was developed. The analysis is performed by gas chromatograph with mass selective detector (GC/MSD) in selected ion monitoring (SIM) mode. Pesticides were extracted from samples with acetone by automated Soxhlet apparatus and this extract was evaporated to dryness for the analysis. The residue was dissolved in hexane, followed by a treatment with a Sep-Pak florisil catridge. Pesticides were positively confirmed by GC/MS, retention times, and ion ratios. This analytical method allows a rapid, reliable, and a good recovery of hydrophilic pesticides. Except far captafol, captan, dichlofluanid and dichlorvos, recoveries of 42 pesticides were over 70%.

• Analytical Science and Technology
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• v.21 no.5
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• pp.403-411
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• 2008

Dimethyldibutyltetradecylmalonamide (DMDBTDMA) extractant was used in a solvent extraction process for a radioactive liquid waste treatment. For the study of radiolysis phenomena, DMDBTDMA was synthesized and the degradation compounds (n-methylbutylamine, tetradecane, 1-tetradecanol) in the DMDBTDMA extractant, irradiated with $^{60}Co$ gamma ray, were identified and determined as radiolysis products by a Fourier transform infrared (FT-IR), gas chromatograph/mass spectrometer (GC/MS) analysis and GC/MS with selected ion monitoring (SIM) mode. Retention behavior of n-methylbutylamine, n-dodecane, tetradecane and 1-tetradecanol in the total ion chromatogram with the standard materials and n-dodecane as the internal standard (ISTD) were 2.35 min., 8.83 min., 10.68 min. and 12.75 min., respectively. In the case of tetradecane, there was a linear relationship between the concentration of the tetradecane and the absorbed dose of the ${\gamma}$-ray irradiated DMDBTDMA.

• Environmental Analysis Health and Toxicology
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• v.24 no.4
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• pp.293-301
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• 2009

This study was conducted to investigate the distribution of the concentrations of selected trace metals and inorganic anions in five types of drinking water samples (mineral spring water, well water, small community water, municipal tap water, and commercial mineral water) collected from Chuncheon, Gangwon-do in 2007. Forty four samples were analyzed for five metals and five anions using an atomic absorption spectrometer and an ion chromatograph, respectively. Arsenic (As) and nitrate (${NO_3}^-$) concentrations in some groundwater samples did not meet the future (10 ${\mu}g/L$) and current (44 mg/L) Korean drinking water standards, respectively. On the other hand, any municipal tap water samples, the sources of which were lake surface water, satisfied the Korean standards. Human health risk assessment results showed that arsenic in all types of water, especially groundwater including commercial mineral water, may pose both noncarcinogenic and carcinogenic effects on the residents. It is concluded that groundwater is not safe drinking water any longer and that a national survey and follow-up measures need to be taken.

• Analytical Science and Technology
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• v.26 no.5
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• pp.315-325
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• 2013

The possibility of acute hepatotoxicity caused by dimethylformamide (DMF) requires regular monitoring of the workers who are using DMF to prevent the occupational disease. The authors performed ambient and biological monitoring of workers involved in synthetic leather manufacturing processes using DMF to assess the correlation between the markers of ambient and biological monitoring of DMF. The authors monitored 142 workers occupationally exposed to DMF from 19 workshops in the synthetic leather and ink manufacturing industries located in northern region of Gyeonggi-do. The subjects answered questionnaire on work procedure and use of personal protective equipment to be classified by exposure type. DMF in air samples collected using personal air samplers, diffusive and active sampler, was analysed using gas chromatograph-flame ionization detector (GC-FID) with DB-FFAP column (length 30 m, i.d. 0.25 mm, film thickness 0.25 ${\mu}m$). Urinary N-methylformamide (NMF) was analysed using gas chromatograph-mass selective detector (GC-MSD) at selected ion monitoring (SIM) mode with DB-624 column (length 60 m, i.d. 0.25 mm, film thickness 1.40 ${\mu}m$). Geometric mean (GM) and geometric standard deviation (GSD) of the ambient DMF was $6.85{\pm}3.43$ ppm, and GM and GSD of urinary NMF was $42.3{\pm}2.7$ mg/L. The ratio of subjects with DMF level over 10 ppm was 44%, and those with urinary NMF over 15 mg/L was 87%. NMF in urine adjusted by DMF in air was $4.61{\pm}2.57$ mg/L/ppm and $9.50{\pm}2.41$ mg/L/ppm, respectively, with or without respirator. There was seasonal differences of NMF in urine adjusted by DMF in air, $7.63{\pm}2.74$ mg/L/ppm in summer and $4.53{\pm}2.29$ mg/L/ppm in winter. The urinary NMF concentration which corresponds to 10 ppm of ambient DMF was 52.7 mg/L (r=0.650, n=128). Considering the difference of the route of exposure which resulted from the compliance of wearing personal protective equipment, the estimated contribution of respiratory and dermal exposure route for DMF was 48.5% vs. 51.5%.

• Analytical Science and Technology
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• v.21 no.6
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• pp.510-517
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• 2008

This study has been described the metabolism and excretion in a healthy male urine collected for 26hrs after oral administration of diclofenac. To detect conjugated metabolites of diclofenac, urine sample was acid-hydrolyzed under the conditions of 6M-HCl at over $110^{\circ}C$ for 1hr. During the acidic hydrolysis process, diclofenac and its metabolites were converted into their corresponding lactam-ring through dehydration reaction. As results of chemical conversion by means of hydrolysis, the structures of diclofenac and its metabolites were also changed acidic to basic forms. However, lactam-ring was degraded by hydroxyl ion at basic condition. Thus, the extraction rate of dehydrated diclofenac and its metabolites was not favored at basic condition. For the determination of trace amounts of diclofenac and its metabolites in urine, trimethylsilylation (TMS) with MSTFA was applied and followed by analysis with gas chromatograph-mass spectrometer. In this study, four metabolites that are formed by the hydroxylation of parent drug were mainly detected. Each metabolite was tentatively identified by both interpretation of mass spectra and comparison with previously reported results. In addition, time profile of urinary excretion rate for parent drugs and metabolites was studied. Finally, the metabolic pathway of diclofenac was suggested on the basis of the elucidation of its metabolites and excretion profiles.

• Journal of Food Hygiene and Safety
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• v.32 no.5
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• pp.411-417
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• 2017

This study was conducted to establish the analysis method for the contents of choline in infant formulas and follow-up formulas by ion chromatograph (IC). To optimize the method, we compared several conditions for extraction, purification and instrumental measurement using spiked samples and certified reference material (CRM; NIST SRM 1849a) as test materials. IC method for choline was established using Ion Pac CG column and 18 mM $H_2SO_4$ mobile phase. The parameters of validation were specificity, linearity, LOD, LOQ, recovery, accuracy, precision and repeatability. The specificity was confirmed by the retention time and the linearity, $R_2$ was over 0.999 in range of 0.5~10 mg/L. The detection limit and quantification limit were 0.14, 0.43 mg/L. The accuracy and precision of this method using CRM were 95%, 2.1% respectively. Optimized methods were applied in sample analysis to verify the reliability. All the tested products were acceptable contents of choline compared with component specification for nutrition labeling. The standard operating procedures were prepared for choline to provide experimental information and to strengthen the management of nutrient in infant formula and follow-up formula.

• Korean Journal of Food Science and Technology
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• v.20 no.6
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• pp.780-786
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• 1988

In order to investigate the most efficient and rapid method for the purification of enterotoxin A from Staphylococcus aureus M 7/1, various methods such as ion-exchange chromatography on Amberlite, and CM-cellulose. gel filtration on Sephadex G-50, 75, 100 and Sephacryl, and fast protein liquid chromatography (FPLC) were applied and compared in terms of purity and speed. Although ion-exchange chromatography on Amberlite resin was good enough to remove other materials in culture medium from enterotoxin, and convenient, and fast method, the purity of this method was less than 70%. However. carboxymethyl ion-exchange column showed to be better purity than that of Amberlite method. The yields of these two methods were about 70% and 75%, respectively. When gel filtration methods on Sephadex G-50, 75, 100 and Sephacryl were applied, the purity was about 90%. Fast protein liquid chromatography was found to be the most efficient method in terms of purity (97%) and speed. The combined method, gel filtration after CM-cellulose column (stepwise elution) treatment can be also used as a efficient method particularly for the purification of large volume of sample.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.684-688
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• 2007

The results of potentiostatic electrolysis of aqueous solution containing fluoride by bipolar packed bed electrolytic cell filled with granular aluminium were summarized. Removal efficiency of fluoride ion which it analyzed with ion chromatograph were 53, 73, 90% in applied voltage. Control the concentration of supporting electrolyte were 10, 30, 50, 70 mg/L and volume of packing material were 0, 25, 50, 75%, respectively, the quantity of electricity was $2.58A{\cdot}hr$ when the concentration of supporting electrolyte was 50 mg/L and the volume of packing material was 75%. As the results of electrolytsis of fluoride aqueous solution containing fluoride 10, 30, 50, 70 mg/L for 3 hours at 10 V, the removal efficiency of fluoride were 93.3, 80, 68.6%. Then the quantity of electricity were 2.58, 3.89, $5.43A{\cdot}hr$ and the fluoride removal amounts per quantity of electricity were 4.0, 3.5, $2.0mg/A{\cdot}hr$.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.25 no.1
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• pp.89-94
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• 2015

Objectives: The objective of this study was to determine characteristics of workers' exposures to airborne total and hexavalent chromium by job title in electroplating processes. Methods: Total Cr was determined through a modified method based on NIOSH Method 7024. Airborne hexavalent Cr, Cr(VI), was sampled and extracted according to NIOSH Method 7600 and analyzed at 520 nm using an ion chromatograph/visible detector. Results: The geometric mean(GM) of total Cr concentrations from all factories was $11.2{\mu}g/m^3$(GSD=4.9). The GM of Cr(VI) concentrations from all factories was $2.84{\mu}g/m$ (GSD=5.2), and the concentrations among factories were significantly different (p<0.05). The Cr(VI) levels were lower than total Cr levels. Total Cr exposure levels were highest among buffing workers ($21.6{\mu}g/m^3$), but Cr(VI) levels were highest among plating workers($4.15{\mu}g/m^3$). The concentrations of Cr(VI) and total Cr from plating tasks was highly correlated(r=0.91). Conclusions: In the electroplating industry, plating workers were mainly exposed to Cr(VI), but others were not. Oxidation-reduction states of Cr and job titles should be considered in the exposure or risk assessments of chrome electroplating factories.